Dataset Information

Calcium-independent disruption of microtubule dynamics by nanosecond pulsed electric fields in U87 human glioblastoma cells.

ABSTRACT: High powered, nanosecond duration, pulsed electric fields (nsPEF) cause cell death by a mechanism that is not fully understood and have been proposed as a targeted cancer therapy. Numerous chemotherapeutics work by disrupting microtubules. As microtubules are affected by electrical fields, this study looks at the possibility of disrupting them electrically with nsPEF. Human glioblastoma cells (U87-MG) treated with 100, 10 ns, 44 kV/cm pulses at a frequency of 10 Hz showed a breakdown of their interphase microtubule network that was accompanied by a reduction in the number of growing microtubules. This effect is temporally linked to loss of mitochondrial membrane potential and independent of cellular swelling and calcium influx, two factors that disrupt microtubule growth dynamics. Super-resolution microscopy revealed microtubule buckling and breaking as a result of nsPEF application, suggesting that nsPEF may act directly on microtubules.

SUBMITTER: Carr L

PROVIDER: S-EPMC5259788 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Calcium-independent disruption of microtubule dynamics by nanosecond pulsed electric fields in U87 human glioblastoma cells.

Carr Lynn L Bardet Sylvia M SM Burke Ryan C RC Arnaud-Cormos Delia D Leveque Philippe P O'Connor Rodney P RP

Scientific reports 20170124

High powered, nanosecond duration, pulsed electric fields (nsPEF) cause cell death by a mechanism that is not fully understood and have been proposed as a targeted cancer therapy. Numerous chemotherapeutics work by disrupting microtubules. As microtubules are affected by electrical fields, this study looks at the possibility of disrupting them electrically with nsPEF. Human glioblastoma cells (U87-MG) treated with 100, 10 ns, 44 kV/cm pulses at a frequency of 10 Hz showed a breakdown of their in ...[more]

PMID: 28117459

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Project description:Glioblastoma multiforme (GBM), is the most common form of adult malignant brain tumor, highly heterogeneous and relatively resistant to therapy with a poor prognosis. As other cancers, GBM starts from a relatively small fraction of poorly differentiated and particularly aggressive cancer stem cells (CSCs), responsible for aberrant proliferation and invasion, rapidly spreading the tumor growth in the other parts of the central nervous system. Due to the extreme tumor heterogeneity, standard therapies (i.e., surgery, chemotherapy and radiotherapy) provide poor positive outcomes and cancers usually recur. Therefore, alternative approaches, possibly targeting CSCs, are necessary for searching effective therapeutic strategies against GBM. Among many emerging new therapeutic strategies, ultra-short pulsed electric fields (PEF) are considered extremely promising in cancer therapy and our previous results demonstrated the capability of a specific electric pulse protocol, characterized by a high pulse amplitude and a short duration, to selectively affect medulloblastoma CSCs preserving normal cells. Here, we tested the same exposure protocol to investigate the response of U87 GBM cells, and of U87-derived neurospheres. By analyzing different in vitro biological endpoints and taking advantage of transcriptomic and bioinformatics analyses, we found that, independently of CSCs content, PEF exposure affected cell proliferation and differentially regulated hypoxia, inflammation and P53/cell cycle checkpoints. PEF exposure also significantly reduced the clonogenic potential, reducing the ability to form new neurospheres, and inhibited the invasion potential. Importantly, exclusively in U87 neurospheres, PEF exposure changed the expression of stemness/differentiation genes. Our results, confirm this physical stimulus as a promising treatment to destabilize the extreme intra-tumoral GBM heterogeneity opening up the possibility to develop future therapeutic strategies mediated by PEF exposure.

Project description:BackgroundUnlike conventional microsecond pulsed electrical fields that primarily target the cell membranes, nanosecond pulses are thought to primarily electroporate intracellular organelles. We conducted a comprehensive preclinical assessment of catheter-based endocardial nanosecond pulsed field ablation in swine.MethodsA novel endocardial nanosecond pulsed field ablation system was evaluated in a total of 25 swine. Using either a low-dose (5-second duration) or high-dose (15-second duration) strategy, thoracic veins and discrete atrial and ventricular sites were ablated. Predetermined survival periods were <1 (n=1), ≈2 (n=7), ≈7 (n=6), 14 (n=2), or ≈28 (n=9) days, and venous isolation was assessed before euthanasia. Safety assessments included evaluation of esophageal effects, phrenic nerve function, and changes in venous caliber. All tissues were subject to careful gross pathological and histopathologic examination.ResultsAll (100%) veins (13 low-dose, 34 high-dose) were acutely isolated, and all reassessed veins (6 low-dose, 15 high-dose) were durably isolated. All examined vein lesions (10 low-dose, 22 high-dose) were transmural. Vein diameters (n=15) were not significantly changed. Of the animals assessed for phrenic palsy (n=9), 3 (33%) demonstrated only transient palsy. There were no differences between dosing strategies. Thirteen mitral isthmus lesions were analyzed, and all 13 (100%) were transmural (depth, 6.4±0.4 mm). Ventricular lesions were 14.7±4.5 mm wide and 7.1±1.3 mm deep, with high-dose lesions deeper than low-dose (7.9±1.2 versus 6.2±0.8 mm; P=0.007). The esophagus revealed nontransmural adventitial surface lesions in 5 of 5 (100%) animals euthanized early (2 days) post-ablation. In the 10 animals euthanized later (14-28 days), all animals demonstrated significant esophageal healing-8 with complete resolution, and 2 with only trace fibrosis.ConclusionsA novel, endocardial nanosecond pulsed field ablation system provides acute and durable venous isolation and linear lesions. Transient phrenic injury and nontransmural esophageal lesions can occur with worst-case assessments suggesting limits to pulsed field ablation tissue selectivity and the need for dedicated assessments during clinical studies.

Project description:BackgroundNumerous approaches have been utilized to optimize mesenchymal stem cells (MSCs) performance in treating osteoarthritis (OA), however, the constrained diminished activity and chondrogenic differentiation capacity impede their therapeutic efficacy. Previous investigations have successfully shown that pretreatment with nanosecond pulsed electric fields (nsPEFs) significantly enhances the chondrogenic differentiation of MSCs. Therefore, this study aims to explore nsPEFs as a strategy to improve OA therapy by enhancing MSCs' activity and chondrogenic differentiation and also investigate its potential mechanism.MethodsIn this study, a million MSCs were carefully suspended within a 0.4-cm gap cuvette and subjected to five pulses of nsPEFs (100 ns at 10 kV/cm, 1 Hz), with a 1-s interval between each pulse. A control group of MSCs was maintained without nsPEFs treatment for comparative analysis. nsPEFs were applied to regulate the MSCs performance and hinder OA progresses. In order to further explore the corresponding mechanism, we examined the changes of MSCs transcriptome after nsPEF pretreatment. Finally, we studied the properties of extracellular vesicles (EVs) secreted by MSCs affected by nsPEF and the therapeutic effect on OA.ResultsWe found that nsPEFs pretreatment promoted MSCs migration and viability, particularly enhancing their viability temporarily in vivo, which is also confirmed by mRNA sequencing analysis. It also significantly inhibited the development of OA-like chondrocytes in vitro and prevented OA progression in rat models. Additionally, we discovered that nsPEFs pretreatment reprogrammed MSC performance by enhancing EVs production (5.77 ± 0.92 folds), and consequently optimizing their therapeutic potential.ConclusionsIn conclusion, nsPEFs pretreatment provides a simple and effective strategy for improving the MSCs performance and the therapeutic effects of MSCs for OA. EVs-nsPEFs may serve as a potent therapeutic material for OA and hold promise for future clinical applications.The translational potential of this articleThis study indicates that MSCs pretreated by nsPEFs greatly inhibited the development of OA. nsPEFs pretreatment will be a promising and effective method to optimize the therapeutic effect of MSCs in the future.

Dataset Information

Calcium-independent disruption of microtubule dynamics by nanosecond pulsed electric fields in U87 human glioblastoma cells.

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Calcium-independent disruption of microtubule dynamics by nanosecond pulsed electric fields in U87 human glioblastoma cells.

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